Vapor generator



Jan. 9, 1945. M. FRISCH 2,366,719

- VAPOR GENERATOR Filed Nov. 22, 1941 2 Sheets-Sheet 2 INVENTOR ATTO RN EY MAEr/N Heat/n H in communication Within the setting are two spaced furnaces l8 and 19 which are disposed adjacent the side walls H and I2 respectively. The inner boundary of the furnace I8 is defined by a vertical baflle Patented Jan. 9, 1945 UNITED VAPOR GEN ERATOB Martin Frisch, New York, N. Y.,assignor to Foster Wheeler Corporation, New York, N. Y., a corporation of New York Application November 22, 1941,Serial No. 420,042

6 Claims. (01. zz-rvn This inventio relates to vapor generators and more particularly pertains to apparatus for generating and superheating steam.

i The invention provides a. multiple furnace superheating steam generator of novel and compact arrangement with which superheat control at all loads on the generator is obtained.

The features and advantages which characterize the invention will be understood from the following description considered in connection thereof, and in which:

- Fig. 1 is a vertical sectionalview of generator embodying the invention;

Fig. 2 is a horizontal sectional view taken on line 2 2 of Fig. 1, and V j if Fig. 3 is a view similar to Fig. 1, showing another form ofthe invention.

Like characters of reference refer to the same or to similar parts throughout the several views.

Referring to Figs. 1 and 2 of the drawings, the steam generator illustrated has vertical refractory side walls H and I2, a front wall I3, a rear with the accompanying-drawings forming a part wall not shown, and aroof l4. Adjacent the roof is asteam and water drum l6, and adjacent the bottom of the setting and intermediate the side walls H and I2 is a flue gas outlet passage with a flue gas outlet ll.

wall 20 which extends upwardly from the bottom of the furnace and terminatesshort of the roof to provide a gas outlet 22 in the upper portion of the furnace. The inner boundary of the furnace I9 is similarly defined by vertical baflle wall 23,

above which is provided a gas outlet 25 in the upper portion of the furnace. Fuel burners 26, which are disposed in the front wall l3 of the 1 setting, fire the furnace l 8, and similar burners 21 disposed in the front wall and operated independently of the burners 26, fire the furnace l 9. Each of the burners 26 and 21 may be individually controlled to fire at any intensity from zero to maximum. The inner side walls 20 and 23 of the furnaces are inclined outwarklly adjacent their lower 1 ends to provide hopper shaped bottoms for each of the furnaces which discharge into suitable ash.

pits 28 and 29 respectively. Extending between theupper drum l6 and a lower drum 30, parallel to the upper drum, is a vertical bank of steam generating tubes 3| which are swept by the gases flowing from the furnace H! to the flue gas out let ll through a vertical gas a steam passage provided by The baffle 32 extends downwardly from the drum baffie 32 and baille wall 23. The lower drum 3i) is positioned at a point above the gas outlet l1.

l6, parallel with the tubes 3|, to a point above the drum 30. A chamber is thereby formed between the lower end of the baffle 32 and the. outlet H" in which chamber the passage between the wall 20 and the baffle 32 and the passage between. the wall 23 and balile 32 merge. A baffle 33 cooperates with baflle 32 to enclose the downcomers 34.

The inner surface of the side wall ll is lined with vertical water wall tubes 36 which extend across the roof portion 14 and are connected at their upper ends to the drum "5, the lower ends being connected to header 3'! which is supplied with circulating water by suitable external downcomer connections, not shown. The inner surface of the side wall I2 is similarly lined with vertical water wall tubes 39 which are connected at their upper ends to the drum l6, and at their lower ends to header 40 which is connected into the boiler circulation. The furnace side of the is lined with water wall tubes 45, and the inner bafiie wall 23 is lined by vertical water wall tubes 42 which extend to the drum I6 from lower header 43 which is connected into the boiler circulation. Adjacent the gas outlet 25, the tubes 42 are spread apart to provide a passage for the gases. That part of the inner surface of the front wall l3 which is at the front end of the furnace l8 surface of the wall l3 at the front of the furnace I9 is similarly lined by water wall tubes 46. It will be understood that those parts of the iimer surfaces. of the rear wall, not shown, which are at the rear ends of the furnaces arelined with similar water wall tubes.

In the form shown, a combination radiant and convection superheater is utilized and is so arsection of radiant heat absorbing surface except at the furnace gas outlet passage 22, where the tubes are spread apart and bent outwardly from the furnace. The tubes 41, which are connected tothe steam space of the drum It in two spaced longitudinal rows as shown in Fig. 1, conduct steam downwardly in one pass to a lower header 49 fromwhich the steam flows upwardly in one pass through the tubes 48 to a point adjacent the roof, where they are formed into a plurality of return bend loops of a convection superheater section 50, which is vertically disposed in the space between the baflle wall and baflles 32 and .33, forming a gas passage for the gases flowing from the furnace I8 to the flue gas outlet I'I'. As shown, the tubes 41 and 48 of the radiant heat superheater section, and the tubes 50 of the convection section, which are arranged for series flow of steam the-rethrough, are continuous with each other, and no intermediate header connections are required. The convection elements 5|! without the use of a by-pass or any other'means of superheat control except for the differential firing provided.

The elimination of intermediate header connections between the radiant and convection sections of the superheater, simplifies and reduces the cost of construction of the superheater and reduces the pressure drop, although intermediate headers may be employedlif desired. The relatively large amount of furnace cooling surface possible with the multiple furnace arrangement,

' results in low temperatures in the ash rejecting are connected to a superheater outlet header 5| which is fixed in position adjacent the bottom of the furnace setting and from which the superaheated steam is conducted to the point of use.

An economizer 52 is disposed in the chamber below the tube bank 3| and convection superheater 50 and between the lower end portions of the furnaces I8 and I9. Other heat recovery apparatus may be disposed in this location if desired.

In operatiomthe gases produced in the lower portion of the saturated steam furnace l9. flow upwardly through the furnace and out thereof through the outlet and downwardly over the tones of the furnaces and thus insures dry ash removal.

similar to; the form shown in Figs. 1 and 2, ex-

' 'cepting that the furnaces are fired from the top form of the invention shown in Fig. 3 is ."Jand baffles are provided to form a gas passage steam generating tubes 3| to the outlet l1 Saturated steam is conducted from the upper drum l6 and flows downwardly through tubes 41 and upwardly through tubes 48, mainly in radiant heat exchange relationship with the gases pro.- duced in the superheater furnace l8. From the radiant section of the superheater, the steam flows through the convection section 50 in convection heat exchange relationship with the. gasesflowing from the furnace I8 through outlet 22 and.

downwardly over the convection section to mergewith gases which have passed over the tubes 3| in the chamber below the lower end of the baffle 32- and thereafter pass over the heat exchanger 52 and out of the setting through the outlet H. The quantity of steam produced will be determined largely by the rate at which the furnace I9 is fired, although some steam will be generated in the water walls of the furnace l8. Inasmuch as the gases produced inthe saturated steam furnace l9 do not flow in heat exchange relationship with the superheater, the degree to which the steam is superheated will be determined by in each of the furnaces through which gases ofcombustion flow from the furnaces into the space. between the furnaces thereafter to flow over the steam generating tubes and the convection section of the superheater in a downward direc tion. As shown in Fig. 3, a vertical baflie 53 is spaced from the baffle wall 54, which is similarto wall 20 of Fig. 1, to provide a vertical gas passage 55 along one side of the combustion chamber;

of thesuperheater furnace it which passage connects at. itslower end with agas inlet 56 and. connects. through a gasoutlet at its upper end with a gaspassage 57 between baffle 54 and a baffie 58 at one side of the bank of steam generating tubes 3|, and through which gases from passage the degree to which the superheater furnace l8 is fired. Furnace |8 may be fired to obtain the superheat temperature desired at any load on the generator, or it may be fired to obtain and to maintain a substantially constant degree of superheat at all loads on the generator.. The superheating characteristics of the combination. radiant heat and convection superheater employed, contribute to the maintenance of a. constant superheat temperature.

With this arrangement, it will be observed that the steam flow in the convection section of the superheater is from the side near the wall 20 tothe side near the steam generating section. Thus the superheater elements at the highest steam temperature are not subjected to the highest temperature gases flowing from the. furnace I8 through outlet 22. v

Since the superheater sections are shielded from the gases leaving one of the furnaces, the steam generator may be started up by firing that furnace only, thus eliminating any necessity for flooding the superheater during starting up periods. This considerably shortens the time ordinarily required to bring the unit onto the line. Also, if a feed water heater were out of service,

a constant steam temperature can be maintained over the 55 flow downwardly over the convection section:

50. of the superheater to the gas outlet H. A vertical baffle 59 is spaced from the baflle wall 60, which is similar to-wal1 23 of Fi 1, to provide a gas passage 6| along one side of the combustion chamber of the boiler furnace l8 whichpassage connects atits lower endwith a gas inlet62 and connects through a gas outlet at its'upper end with agas passage between the baffles 50 and 58 in.- which the steam generating tube bank 3| is disposed.

In. operation, the gases produced in'the upper portion of the boiler furnace |9-,' flow downwardly: and enter the passage 6| through the inlet 62 thereafter flowin upwardly. through passage 6 The gases from the furnace It are discharged from the passage til-through the outlet at the top thereof and flow downwardly over the steam generating tubes 3| 'to the setting outlet 'I1 through the chamber below the lower end of the baffle 58 and over the tubes of the economizer 52. The gases producedin the upper portion of the superheater furnace l 8, flow downwardly through the furnace; enter passage 55 through inlet 55 and fiowupwardly through passage 55. The gases from the furnace l8 are discharged from passage 55 through the outlet at the top thereof and flow downwardly over the tubes of the convection. section of the superheater to, the setting outlet. H through which outlet thegases flow after merging'inlthe. chamberibelow" the lower end ofthe baflie '58 with the, gases which have passed 5 tubes, 3| and flowing over the economizer It will be understood that changes may be made in the form, location and relative. arrangement of the. several parts: of the steam generators disclosed withoutdeparting. from the principles of the invention; Consequently, the invention isnot to be limited excepting by the; scope of. theap-y s s I.

What is claimed is: l 1. Vapor generating apparatus comprising a setting, walls so positioned within the setting as to form spaced furnaces therein, means for firing each furnace, a gas outlet leading from each furnace to the space between the furnaces near one end of the space, an outlet for the setting near the other end of said space, a partition between said walls positioned to divide said space into two passages each of which connects to a furnace gas outlet and merges with the other passage one end of the space, an outlet forthe setting near the other end of said space, a partition between said walls positioned to divide said space into two passages each of which connects to a furnace gas outlet and merges with the other passage short of the setting outlet so as to form a chamber between the point of merger and the setting outlet, vapor generating surface in one of said gas passages, a superheater having a part thereof disposed in the other gas. passage and another part in the furnace adjacent said other passage, and a heat exchange device in said chamher.

3. Vapor generating apparatus comprising a setting, walls so'positioned within the setting as to form spaced furnaces therein, the lower portion of saidwalls being vertically inclined away from each other thereby forming" an inclined bottom for the furnaces with which the wall is associated and providing an enlarged portion for the space between the furnaces at the lower end thereof, means for firing each furnace, a gas outlet leading from the upper part of each furnace to the space between the furnaces near the top of the space, an outlet for the setting near the bottom of the space, a partition between said walls positioned to divide the space into two passages each of which connects to a furnace gas outlet and merges with the other passage short of the setting outlet, means forming a chamber in the enlarged portion of said space between the point of merger of said passages and the setting outlet, vapor generating surface in one of said gas passages, vapor superheating surfacein the other gas passage, and 'a heat exchange device in said chamber.

4. Vapor generating apparatus comprising a setting, walls so positioned within the setting as to form spaced furnaces therein, means for firing each furnace at the lower portion thereof, a gas outlet leading from the upper part of each furnace to the space between the furnaces near the top of the space, an outlet for the setting near the bottom of said space, a partition between said walls positioned to divide said space into.

two passages each of which connects to a furnace gas outlet and merges with the other passage short of thesetting outlet so as to form a chamber between the point of merger and the setting outlet, vapor generating surface in one of said gas passages, vapor superheating surface in the other gas passage, and a heat exchange device in said chamber.

5; Vapor generating apparatus comprising a setting, walls so positioned within the setting as to form spaced furnaces therein, means for firing each furnace, baflie means forming a gas outlet passage in the furnaces extending along one of said walls, the gas outlet passage being in communication with the furnace near one end of the furnace chamber and in communication near the opposite end of the furnace with one end of the space between the furnaces, an outlet for the setting near the other end of said space, a partition between said walls so positioned as to divide thespace into two passages each of which connects to a furnace gas outlet passage and merges with the other short of'the setting outlet to form a chamber between the point of merger and the setting outlet, vapor generating surface in one of said gas passages, vapor superheating surface in the other gas passage, and a heat exchange device in said chamber.

6. Vapor generating apparatus comprising a,

setting, walls so positioned within the setting as to form spaced furnaces therein, burner means positioned at the top of each furnace to direct a stream of gases of combustion in a substantially vertical direction toward the bottom of the furnace, baflle means forming a gas outlet passage in the furnaces extending alongone of said walls, the gas outlet passage being in communication with the furnace near the bottom of the furnace chamber and in communication near the top of the furnace with the upper portion of the space between the furnaces, an outlet for the setting near the bottom of said space, a partition between said walls so positioned as to divide the space into two passages each of which connects to a furnace gas outlet passage and merges with the other short of the setting outlet to form a chamber between the point of merger and the setting outlet, vapor generating surface in one of said gas passages, vapor superheating surface in the other gas passage, and a heat exchange device in said chamber.

MARTIN FRISCH. 

